We have, during the past year, shown that aspirin preserves blood flow at the infarct margin, that nitroprusside significantly reduces ultimate infarct size in two-thirds of treated animals and that steriods have no effect on infarct size. All this work was done in baboons which we have shown provide a superior model for studying the efficacy of interventions. During the forthcoming year, using our baboon model, we are going to evaluate retrograde coronary sinus perfusion, balloon pumping and aspirin on actual modification of infarct size. We will also assess the role of drug interventions on prolonging the period of myocardial salvage resulting from coronary reperfusion. Finally, we are doing methodological work with an intramyocardial electrode to characterize and define the border zone.